Photographic emulsions



' idye. 1 l

A large variety of polymeric dyestuffs contain- Patented Jan. '22, 1946 UNITED STATES PATENT OFFICE duPont deNemours & mm r w hn ns on 5 'Del.. 3. corporation'of Delaware H application March Z, 1943, sal -1s... 4717.165

7 Claims.

This invention relates to new chemical compounds and to their preparation. More particularly, it relates to new polymeric dye intermediates and polymeric dyes and to their preparation and use. Stil1 more particularly it relates to polymeric com-pounds which have photographic sensitizing properties. Still more particularly it relates to polymeric organic compounds containing cyanine dye components and to their preparation and use.

An object of this, invention is to provide new types of polymeric organic compounds. A further object is to provide a new class of polymeric dye intermediates. A still further object is to provide polymeric dyes containing a plurality of cyanine dye components. Yet another object is to-providea'simple and economical method of preparing polymeric dye intermediates and dyes. Another object is' to provide new photographic compositions such as silvenhalide emulsions, con

taining polymeric dyes, :and treating solutions therefore. Still other-objects will be apparent from the following description of the invention. It has been found that-new polymeric compounds ca'ngbe madejby reacting a heterocyclic nitrogen base witha polyfunctional organic compound containing a plurality of functional groups each of which is capable of forming quaternary ammonium salts with ternary nitrogen compounds. At least one -mol of'base is used for each functional group. The resulting polymeric products which contain a polyvalent organic radical. between or linked to nitrogen atoms of the heterocyclic nitrogen compounds can then be condensed with'other compounds to form still other types -or'modified types of polymers.

The invention can be applied to a large and diverse group of heterocyclic nitrogen compounds containing (1) a trivalent heterocyclic nitrogen capable of forming quaternary or cyclammonium salts with alkylsalts e. g. ethyl iodide, methylap-toluene sulfonate, etc., and (2) a reactive group. The resulting bis-', tris-., etc. or polymeric salts :arenew and useful compounds. Since they still {contain reactive groups they can (a) be'contdensed with other dyestufl components to form ipolymeric dyes ;or (b) condensed with organic lcompounds to dorm intermediates with a differient reactive group which may be subjected to a ,dye condensation reaction to form a polymeric iing at least two dyestuff nuclei linked through :heterocyclic nitrogen atoms by a polyvalent hydrocarbon radical having an acyclic carbon atom .15 atoms 7 thereof.

-. .nnimportant aspect :Of the nve o 5 n Baye whe i th wa g g le lea twotim s. he u lei being o a divalenthydrocarbon radical attached (through a non-aromatic ,car-

non.atom;oratoms to@heterocyclic nitrogen .atoms' nuclei. In other words .the dye nuclei s ar twonrmamtime tpdlyzmers consi ;of. tw ol.heterocyclicnitrogen-nuclei which are connected to each other by a chain of conjugated double "bonds between hetero-nitrogen One .or more of the nitrogen atoms of each nucleus is attached to a divalent hydrocarbon radical as previously explained to form the polymeric structure. I r

In the case of the monomethine cyanines and '20 polymethine-cyanines two heterocyclic nuclei are joined through a methine or hydrocarbon substitut'ed. methine -CR=) group or a polymethine -(,.-CR,=)n group which is attached to carbonatoms thereof. In the formulae R is hydrogen or 25 a hydrocarbon =radical and n is a small positive som thi W9 n lud c rb q -hq r n es tiicer gq a ji'n sls .hydrocarbonv radical which is attached to 3 hetero nitrogen atomsthrough an acyclic carbon atom or atoms.

Polymeric dyeshaving no linking chain such as the apocyaninesas well astho'se containing non carbon atoms in the linking/chain such as the 3 cyazines and carbocyanines which contain a nitro en. atom er. 1 p ur y o n tro en atoms ilpspmay form; partof aring hav a. cha n of onju at wee het mz itm ato 1 ;e ..n -'fl%2: ,b v dival nt h s e radical attached through hetero-nitrogen; atoms and acyclic carbon atoms.

Polymeric merocyanine dyes. which contain at least two merocyanine dye nuclei linked by a divalent hydrocarbon radical which is attached I to heterocyclic nitrogen 'a-toms'through an acyclic carbon atom constitute 1a further aspect of the invention.

Polymeric dyes obtainable in accordance with the teachings hereof fall within the general formula:

: whereinR is a cyanine dye nucleus, A is a polyhe invention. Q lhese comvalent hydrocarbon radical and n is a positive integer.

These dyes are made as previously explained from bis-type quaternary salts of the general formula:

wherein Z and Z are the same or difierent and constitute a reactive group capable of dye condensation and Y and Y are the same or different and constitute the atoms necessary to complete a heterocyclic nitrogen nucleus.

both of the N atoms may be part'of a salt group.

The invention will be more readily understood by a consideration of a more specific aspect thereof. A heterocyclic ammonium base containing a reactive group which can be used in cyanine dye condensations such as methyl benzothiazole is reacted with a polyfunctional agent such as propylene di-bromide and a bis-type quaternary salt is formed. The resulting salt One or v which now-contains two reactive groups can then be subjected to a dye condensation reaction, for instance, with an ortho ester in the presence of an acid binding agent to form a polymeric dye.

.The first mentioned reaction might be regarded as proceeding in accordance with the equation:

Based upon this formula it is possible that the resulting polymeric quaternary salt might have one or two ternary nitrogen atoms by reason of one or two molecules of HBr splitting off if a strong base is present. Following this theory, it is possible that the resulting dye intermediate may have the formula:

Assuming the polymeric quaternary salt has Formula 4 or 3, the reaction with ethyl ortho formate in the presence of an acid binding agent,

e. g. pyridine'under reflux conditions, might be regarded as taking place in the following two manners:

- or G-menibered heterocyclic nucleus; is, =used preparedby fheating bis t ype salts or Formula 3 with agentswhich will remove HBr or HXth'erefrom wherein X is an anion. hea'tingin the presence ofa strong base such as-caustic 's oda will result in compounds of Formulae 4 and 5, the particular type depending "upon the duration "of rreaot ion and concentration of reactants. Compounds of the "last mentioned type, Whicheare polymeric bases, "however, do not undergoall of the dye condensation:reactionswhich can "be applied.'to-tl'rose o'fFormul-ae 3and 4.

Theinvent-ion,ina broad sense, may be applied to any heterocyolic' nitrogen base containing a reactive group which can be condensed to form a dye. y In addition toreactive methyl and methylene groups mention ismade -of reactive halogeng-roups, alkyl-thioand-alkyl- "'seleno-e'ther groups, acylrne'thylene derivatives formed by the condensation of a reactive "methyl group with an 'acyl halide, i.1-'e'; acetyl chloride, propionyl' chloride, crotonyl chloride, benzoyl chloride, -"etc., thione I or -=selenone groups, I 'nitro soam'ine groups; beta-anilinovinyl groups, amino groups; and alpha-ethyl groupsfetc.

Some "of the aspectsof the invention are illustrated below wherein a 'heterocyclic nitrogenbase having "in one of its ta'utom'eri'c forms 'one'of the formulae: l

wherein R an'd' R" represent a hydrogen atom :or, a liydrocarbon radical, e. aialkyl, Y';represents as be'fore s'tated' I as a reactant with the poly'functional reagent, n

"is a small positive integer and X is halogen -ie'. g.

-C1,'-";Br; I. In-the above formulae Y may form with the carbon and nitrogen atoms :a fi-memi b'ered heterocyclic nucleus containing twonuclear non-metallic atoms other than carbom oneof' which non-metallic at'om, such as oxygen su-Ifur,

selenium or a divalent hydrocarbon radical such I l I v R4l s,

asfwherein R1 and R2 arealkyl radicals, or a 6- fmeinbered heterocyclic nucleus containing one the balance 'carbonatoms.

By heterocyclic nucleus as described above, it is intended that both substituted and unsubstituted heterocyclic ring are included, including, for instance, benzoxazoles, benzthiazoles, benznuclear hetero atom, e. g. trivalentrfitrogenand "oselenazoles, benziminazoles, thiazoline and the corresponding naphthazoles and. anthracenoa- -zoles, etc., pyridine, quinoline, naphthopyridi'ne, etc.- Various types of substituents maybe present in the benzene nuclei, 'e. g. hydrocarbon, hydroxy, alkoxy, amino and substituted amino groups. Substituents may also be present inthe pyridine nuclei.

In a further aspect, another class of {heterocyclic compounds which maybe employedin the invention corresponds to the following formula:

wherein W isaeither =C='S,' =C=Se,*=C=Te,=or =C=O :and Z represents the non-metallic atoms necessary to complete a five-membered 'ketoheterocyclic nucleus containing two nuclear nonmetallic atoms other than carbon, at least one of whichis' trivalent nitrogen and another of which is divalent when other than nitrogen, and CH2 is "intracyclic reactiveqmethylene. groups.

Compounds of this type include a thiazo1one,an

oxazolonaan imidazolone, a pyrazolone, etc.,1for

example, compounds such :as :rhodanines, Q- thio- 2,4(-3,5) 'oxazold'eione nucleus, 'hydantoins :and nitrogen substituted derivatives, pyrazolones and thio-pyrazolone's in addition Z represents the non-metallic atoms necessary to, complete :a .six=

membered keto-heterocyclic nucleus for example, a "six-membered heterocyclic nucleus icon'tainin @two nuclear trivalent nitrogen atoms and four nuclear carbon atoms such as barbituric acids,zand

a reactive 'groupzsuch as an intracyclic reactive methylene gr0up. 1,

:Various types of polyfunctional organic hydro- ;carbon compounds can be used in the production of .the bis-type quaternary :salts and bases. Among the useful bifuncti-ona-l types are alkylene polyhalides, cycloalkylene polyhalides, alkyl estters of'alkylene and cycloalkylenersulfonic acids,

alkyl esters of arylene sulfonic acids, dialkyl estersaof 'alkyl'ene disulfuric acid andgmixed compounds containingthe above' functional groups.

The bis-type quaternary salts and bases can be 'dye condensed to form polymeric symmetrical dyes having the general formula 1 wherein the Rs are the, same or different in variousmanners which will be outlined below.

Polymeric erythroand xanthoapiocyanines can be'prepared :by heating a bis-type quaternary salt v 10f .quinoline inanalcoholic iirutassium hydroxide the non metallic atoms 'necessarylto (complete a solution e. :g. methyl or ethyl alcohol -so1uticn.

Polymeric a'zoc'yanines can be obtained by condensing a bis-type quaternary salt or a heterocyclic nitrogen base which contains an amino group in the alpha position to the cyclic nitrogen atoms e. g. ethylene bis c-aminobenzothiazole'di chloride, with an u-halogen substituted alkyl quaternary salt e. g. a-iodoquinoline ethyl. chride, in the presence of sodium ethoxide. Or alternatively the bis-type salt may contain a reactive halogen and the other cycloammonium salt an amino group in the alpha-position to the nitrogen atom.

Polymeric carbocyanine dyes may be made by condensing a N:N' alkylene bis-type derivativ of a heterocyclic nitrogen base containing a methylene group in the position alpha to the nitrogen atom with compounds of theformula:

wherein W is a group such as halogen, amino, alkyoxy, acyl, etc., in the presence of an organic acid anhydride, e. g. acetic anhydride, and following said condensation by reacting the resulting products with a hydrocarbon salt of a quaternary nitrogen compound containing a reactive methyl group in the alpha or gamma position to the nitrogen atom.

In addition to the ortho ester method of preparing polymeric carbocyanine and centrally substituted Carbocyanine dyes set forth above, other polymeric dyes can be obtained by reacting one mol of the bis-type quaternary salts containing reactive groups with diarylformamidine or a C- al-kyl substituted diarylformamidine in the presence of acetic anhydride and a further reactin of the intermediate thus formed with another mol of the same bis-type quaternary salt or a difierent heterocyclic quaternary salt having a reactive group e. g. methylene, methyl, mercaptoether, halogen, etc., group.

Symmetrical polymeric dicarboxyanines can be obtained by reacting two mols of the polymeric bis-type salts with one mol of anilido-acrolein anil in the presence of an organic nitrogenous base having a disassociation constant greater than ammonia, e. g. pyridine, dimethylamine, trimethyl amine, diethylamine, triethylamine,.dimethyl amine, etc., or a strong inorganic base, e. g. potassium hydroxide or sodium hydroxide. In a similar manner, beta-ethoxy acrolein acetal or propargyl acetal can be, used in place of said anil.

The production of symmetricalpolymeric tricarbocyanines may be accomplished by reacting two mols of the polymeric or bis-type quaternary cycloammonium salts containing reactive groups, with one mol of glutaconic aldehyde dianilide in the presence of a base such as pyridine, piperidine, tetramethylene diamine-L4, etc.

By condensation of the polymeric quaternarycompound in the presence of an acid binding agent, e. g. piperldine, dimethylamine, etc.

' Carbocyanine dyes of a polymeric type can be prepared bycondensing the bis-type or polymeric cyclammonium quaternary salt containing reactive methyl ormethylene groups in thealpha or gamma position to the cyclic nitrogen atom with 1 an acyl methylene derivative of a tertiary cyclammonium compound 1. e. 1 acetyl methylene 2 ethylbenzothiazoline, ;etc., in the presence of an acid binding agent, e. g. pyridine, vdirnethylamine, etc. Polymeric 2-4 cyanines or carbocyanines can be prepared by condensation of 2 molecules of an alpha; gamma di-substituted cyclammom'um quaternary salt containing reactive halogen e. g. iodine, or methyl substituents in the presence of sodium ethoxide in alcoholic solution.

Carbocyanine dyes of a polymeric structure can be obtained by the, condensation of 2 molecules of an alpha methyl cyclammonium quaternary .orthoaminothiophenols and orthoaminoselenophenols with a dibasicorganic acid containing 3 to 8 carbon atoms, converting the. product into a bis-type quaternary salt after the manner described above and condensing said salt with an ortho ester type of an organic acid.

Polymeric carbocyanine dyes may be prepared by the reaction of three mols of a bis-type cyclammonium salt containing a reactive methyl or methylene roup such as hexamethylene bis a-methyl benzothiazole bromide in the presence of 3 mols of an organic base such as piperidine and triethylamine, apicoline, etc.

Carbocyanine dyes having a polymeric structure may be prepared by condensing 1 mole of a bis type quaternary "cyclammonium salt having a reactive methyl or methylene group with one mole of an alkyl ester of an arylated thioimide such as ethylisothioacetanilide in the presence of an or ganic monocarboxylic acid anhydride e. g. acetic anhydride and further condensing the product with an additional mole of a monomeric quaternary cyclammonium salt of the nam or difierent type of heterocyclic basein the presence of an organic acid binding agent e. g. pyridine, piperidine, etc.

Cinnamylidine derivatives which have a polymeric structure may be prepared by condensing p-dialkyl amino cinnamic aldehydes with a bistype cyclammonium quaternary salt containing a reactive methyl group substituted in the position alpha to the nitrogen atom.

Polymeric cyadiazines can be prepared by condensing heterocyclic nitrogen bases having a hydrazine grouping (i. e. =N--NH2) in the position alpha to the nitrogen atom with an aldehyde of a bis-type or polymeric cycla'mmonium quaternary salt.

Trinuclear cyanine dyes having a polymeric structure can be made by reacting a 2,4-dihaloseno typ'e quaternary salt with two molsci a cyclammonium salt containing ,a reactive alkyl ing solvent' g V i Polymeric merocyanine dyes. can be made from groupeg. alpha-methylbenaothiaaolein .the "presen e of a r n bas c n nsin t- P f ably.--atertiary organic base.

Polymeric cyazine-dyes may be produced: by reacting a bis-type quaternary or. cyclammonium.

salt havingan amino or imino groupin the alpha or; gammaspositionto the nitrogen atom with either a' quaternary salt ofa; f iur-ther heterocyclicnitrogen compound, having: a. reactive aminovinyl thioetheror selenoether' grouping (including the reactive groupingof analkyl salt of an N- alk-yl thioneor selenone) or substituted; forms-thereof in the alpha or gamma; POs-it ionto a: nitrogen.

iss ct-.1, be prepar d hr portant class. of; dyes may be. represented as having. one; of the followingrformulae:

nary salts .of pyridinium type bases substituted. in

the gamma position by cyanide groupings; in the presence of alcoholic potassium hydroxide or a similar'strong'base.

y n n dyes having a polymeric structure can be prepared by the reaction of a compound such as. phenyl rhodanine with abis-type quaternary salt. or an aminovinyl azole such as l-(B-acetanilido vinyl) benzoxazole in the presence of basic. condensing. agent, e. g. pyridine; di-

' methyl aniline, etc; Q

Polymeric psuedocyanine dyes can be prepared by reacting abis-type or polymeric cyclammonium salt of quinaldine with diorthoformylethylaminodiphenyl disulfide in hot pyridin oranothertertiaryamine. j I

'Tri'carbocyan-ine dyes having a polymeric structurecan be prepared by the reaction of bistypeor polymeric quaternary cyclammonium compounds containing a reactive'methyl group with acompound such as dinitrophenyl pyri-- dini'um chloride or a pyrid-inium cyanohal'o'genide in the presence. of a strong organic: base such as tertiary amino.

Polymeric unsymmetrical tricarbocy-anines can be prepared bythe reaction of a bis-type or poly meric. quaternary ammonium sad-tot a heterocyclic basev containing in alpha-position to the nitrogen atom a methyl E 1 1?! q pable of reactionwi-th an amino epsilon imido alpha-gamma pentadiene hydrohalogenide inthe presence of an acid bindthe bis-type or polymeric cyclammonium salts containing a;group;.;='-CH'CHO attached toF-a-carbon atom in the heterocyclic. ring-with an 'acidof theformula RCOg-NH- -CHzGQDH WhereinR'. is a alkyl oraryl: in thepresenceof a water-binding agent; particularly anhydrides of fatty acids of 2 to 4 carbon atoms. Alternatively the bis-type salts containing: a reactive methyl group in; the alpha, or gamma positiom to the. nitrogen atom can. be treated with derivativestformed by thelnvteraction of a diaiylformamidine-- and a. methylehenylnyrazolone or; a .diphenylpyrazolone.

From the aboved-iscussion, itwill be apparent that. the invention comprehends the production: of

flux distillation just b an Y are thesame or atoms. necessary to completea pyridine, dialkyl In each of Formulae 14. a and, b and 15 Y and. difierent. and. constitute the indolenine. or azolel nucleus including. anfimine azolenucleus, R: ishydrogen or a monovalent. hy-. dro carbon radical, X is the negative. radical. ofan acid, A is a plete. a, pyridine. nucleus. the .conjugatediacylic chain. may be attached. to alpha carbon atoms; The non-cyclic. types. of carbocyanine or substituted, carbocyanine polymersv may be, turther'.

exemplified by the following formula which shows the. relationship of the polymer chain and end groups. I H

'- The polymeric cyanine. dye obtainable by the invention arevery well suited for sensitizing gelatino silver halide emulsions. and the invention includes silver halide emulsions sensitized by means of the noveldyes as Well as processes of sensitizing suchfemulsions with the dyes. The

-dye"may be incorporated in theemulsions at any production orthe finished desired stage in its I a solution .of

emulsion layer may be bathed in the dye. 1 The invention will be more fully illustrated but is not intended to be limited by the following examples; 1 I

' EXAMPIiE'I iii propylene. thiacarbocyanine Polymeric lei-3' I I bromide) I A 3 portion of 2-methylbenzothiazolewas mixed with 2 g. oi propylenedibromide and the mixture heated for "twelve hours at l30-140 C. The product was then dissolved in 20 ml. "of pyridine, heated to a temperature at which reand 5, ml. of ethyl As the orthoformic deep magenta color for one hour. the

orthoformate were added. ester entered the reaction a obtained. After refluxing e new ass acir m me ie Q a ntdivalent hydrocarbon radical, When. i;- constitutes; the atoms necessary to. commixture was cooled, diluted with ether and filtered. The solidwas recrystallized from al- 001101 and dried. Th reaction yielded 0.3 grams of green crystals.

This dye, dissolved and added in a concentration of 35.5 milligrams per liter to a gelatino silver bromide emulsion, extended the sensitivity to 6300 A. with a maximum at 6000 A. and a minimum at 4.800 A. In a concentration of 23 milligrams per liter in a silver chloride emulsion the sensitivity was extended to 6500 A. with a maximum at 6000 A. and a minimum at 4800 A.

In the accompanying drawing Fig. 1A is the curve from a spectrogram of a non-dye sensitized silver chloride emulsion. Fig. 1B is a spectrogram of a similar gelatino-silver chloride emulsion containing the dye of Example I.

EXAMPLE II Polymer (3-3'-dipropyZene-9-methyl thiacarbocyam'ne bromide) The compound 3-3'-propylene bis Z-methylbenzothiazole dibromide was prepared from 3 grams of 2-methylbenzothiazole and 2 grams of proylene dibromide by a process similar to that described in Example I. The resulting compound was then dissolved in 20 ml. of pyridinto which was added 6 ml. of ethyl ortho-acetate after the solution had been brought to a boil in a flask fitted with a reflux condenser. Refluxing was continued for one-half hour, following which the material in the flask was cooled, extracted with ether and recrystallized twice from ethyl alcohol. The reaction yielded 0.4 gram of soft bronze gree crystals.

A concentration of 35.5 milligrams of this dye added to a liter of a gelatino silver bromide emulsion extended the spectral sensitivity of the emulsion to 6300 A. Sensitivity maxima were producedat 5400 A. and 5900 A., with minima at 5100 A. and 5600 A. In a silver chloride emulsion at a concentration of .23 gram per liter the sensitivity was extended to 6500 A. with a maximum at 6000 A. anda minimum at 4700 A. In Fig.2 of the drawing there is shown a spectrogram of the resulting emulsion. The sensitivity curve of a gelatino silver chloride emulsion containing this dye is shown in Fig. 3 of the drawing.

EXAMPLE III A mixture of '3 grams of 2-methylbenzothiazole and 2 grams of propylene dibromide was heated for 4 hours at 130 C. The product was taken up in 40 ml. of dry pyridin, heated to refluxing and 5 ml. of ethyl ortho propionate added thereto. The mixture was refluxed 4 hours during which time a magenta color formed. 'At the end of the reflux distillation the mixture was poured into cold water, producing a dark, tacky solid. The precipitate was washed with water, recrystallized from alcohol and dried. The substance could not be efiectively crystallized and after the treatment described, still remained a ummy, dark mass.

EXAMPLE IV Three grams of 2-methyl benzothiazole were mixed with 2.44 grams of hexamethylene dibromide and heated to 130 C. for 4 hours. The product was taken up in 40 ml. of pyridine and pie color was produced.

The solution was diluted to 2 liters with water containing an excess of potassium iodide, whereupon a heavy oily liquid was precipitated. This oil was separated, boiled in 500 cc. of alcohol, filtered while hot and 50% of the solvent removed from the filtrate by evaporation. When cooled, a quantity of soft, gummy material was precipitated; when other was added to the mixture, additional precipitation occurred. Attempts to recrystalliz'e the compound fromabsolute alcohol were unsuccessful so the compound was evaporated to dryness, redissolved in alcohol and then crystallized by the rapid addition of a large volume of ether. The precipitated crystals were filtered off, washed in ether and weighed, A yield of 2 grams of green crystals were obtained by the process.

A 35.5 milligram portion of this dye added to a liter of a gelatino-silver bromide emulsion produced an extension of the spectral sensitivity to 6300 with a maximum at 6000 A. and a minimum at 5100 A. A concentration of 23 milligrams per liter in a silver chloride emulsion extended the sensitivity to 6400 A. with a maximum at 6000 A. and a minimum at 4700 A. The spectrogram of the latter emulsion is illustrated in Fig. 4 of the drawing.

EXAMPLE V Polymeric (3-3'-dihexamethylene-Q-methyl triacarbocywnine iodide) Three grams of Z-methylbenzothiazole were mixed with 2.44 grams of hexamethylene dibromide and the mixture heated for four hours at C. The product was taken up in 40 ml. of dry pyrid ne which was raised to the boiling point, following which 5 ml. of ethyl orthoacetate was added thereto. Refluxin-g wascontinued for f 0ll1' hours and a magenta color was produced. When treated with water and potassium iodide as'in the preceding example, a dark, tacky solid was precipitated. This was filtered ofi, washed with water, recrystallized from 500 ml. of alcohol, dried and weighed. A 0.1 gram yield of dark, purplish crystals was obtained.

This dye added to a gelatino-silver chloride emulsion ina concentration of 23 milligrams per liter extended the sensitivity to 6200 A. with a maximum at 5800 A; and a minimum at 4700 A. See Figure 5 of the drawing which shows the sensitivity curve of the emulsion.

EXAMPLE VI Polymeric (3-3'-dihea:amethylene-9-ethyl thiacarbocyanine iodide) The exact procedure of Example V was repeated using ethyl ortho propionate in place of ethyl. orthoformate. The product was a tacky solid. The sensitivity curve of a gelatino-silver halide emulsion containing this dye is shown in Fig. 6 of the drawing.

It is to be understood, however, that the invention as outlined above is not limited to the reaction of heterocyclic nitrogen bases containing a single heterocycllc nucleus with the poly functional reagents to produce polymeric or bistype salts. 0n the contrary, it is equally applicable to the bis-azoles such as the benzo-bisabove has been devoted to a preferred'aspect of the invention, namely, that in which'the cation constitutes the entire polymeric cyanine dye base and the anions are attached to heterocyclicnitrogen atoms. However, it is clear from paras graphs A to E that the invention comprehends a type wherein the anion is polyvalent and the cations are simple cyanine dye bases. In the last mentioned type the linking radical forms an anion bridge between the nitrogen atoms of the respective nuclei. Furthermore, the nitrogen atoms are pentavalent.

Various types of acid binding agents or solvents can be used in the dye condensation reactions. The particular one chosen depends somewhat on the initial reactants and the-type of dye ultimately desired. Suitable agents include caustic soda, sodium alcoholates, e. g. sodium methylate, sodium ethylate, alcoholic caustic soda, alkali metal carbonates, orthophosphates and tetraborates, acid anhydrides, e. g. acetic anhydride, propionic anhydride, etc. alone or in the presence of sodium or potassium acetate, sodium nitrite, alkyl nitrites, organic nitrogen bases, e. g. pyridine, methyl pyridine, piperidine, methylamine, ethylamine.

After the dye condensations have been completed, the resulting polymeric cyanine salts may be converted into any'desired specific salt by metathesis. If a bis type alkyl disulfonate is formed in the initial reaction, for instance, it can be converted into the corresponding bromide by treatment with aqueous sodium bromide. The bromide or alkyl disulfonate can be converted to the iodide by treatment with aqueous sodium iodide. Perchlorates can be obtained by the addit on of K0104 to polymeric cyanine salts. Less soluble salts can be formed from the more soluble salts by a similar double decomposition reaction. Soluble salts of the polymeric cyanines can be made from halide salts by refluxing with a' silver salt of the desired anion e. g. Ag2SO4, etc.

In place of the specific ortho esters of carboxylic acids set forth in the above examples can be substituted any ester of this type which is capable of reacting with the heterocyclic nitrogen compounds having a reactive methyl or methylene group. Suitable esters include trimethyl ortho-propionate, methyldiethyl n-caproate, methyldiethyl ortho-isocaproate, trimethyl ortho-valerate; trimethyl ortho formate, trimethyl ortho-benzoate, trimethyl ortho-p-toluate, t imethyl ortho-gamma-phenoxy-butyrate, trimethyl ortho-phenyl-acetate, ethyl ortho-furoa te, trimethyl ester of cyclohexyl carboxylic acid.

The polymeric cyanine dyes obtainable by this invention which contain a hydrocarbon radical between the nitrogen atoms of heterocyclic nitrogen nuclei as has been previously pointed out, are particularly useful in the preparation of spectrally sensitized photographic silver halide emulsions. They are not limited in their use to any particular type of silver salt, but actually can be used with simple and mixed silver halide emulsions and mixed emulsions in general. They definitely have utility in silver chloride, silver bromide, silver-chloride-bromide, silver-bromideiodide, silver-chloride-bromide-iodide, etc., emulsions. They are also useful in mixed emulsions for instance. those having the proportion of 25% chloride emulsions to 75% chlorobromide emulsion to 75% chloride emulsion to 25% chlorobromide emulsion. The dyes can be added to one or more of such emulsions prior to mixing.

In the preparation of photographic emulsions containing such novel dyes, it is necessary only to bring the dye into intimate contact with the light sensitive silver salt layer. This can be accomplished by dispersing the compounds in the emulsions before coating the light sensitive layers or afterwards by bathing or impregnating the layer with the polymeric dyes. It is convenient to add the dyes to the emulsions in the form of solutions in appropriate solvents. The solvent must, of course, be compatible with the emulsion, substantially free from any deleterious effect on the light-sensitive materials in the emulsions and.- capable of dissolving the dyes. Methanol is a satisfactory solvent for my'new dyes. Acetone can be employed. The dyes are advantageously incorporated in the finished washed emulsions and should be uniformly distributed throughout the emulsions.

The concentration of my new dyes in the emulsions can vary widely, e. g., from about 2 to 100 mg. per liter of ordinary flowable gelatino-silverhalide emulsion. The concentration of dye will vary according to the type of light-sensitive materials employed in the emulsion and according to the effects desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art, upon making ordinary tests and observations customarily employed in the art of emulsion-making. To prepare a gelatino-silver-halide emulsion, the following procedure is satisfactory: A quantity of the dye is dissolved in methyl alcohol or acetone and a volume of this solution (which may be diluted with water) containing from 2 to 100 mg. of dye is slowly added to 100 cc. of a flowable gelatino-silver-halide emulsion with stirring. Stirring is continued until the dye is thoroughly incorporated in the emulsion. Ordinarily from IO-to 20 mgs. of our new dyes per liter of emulsion suflice to produce the maximum sensitizing efiect,

The products of this invention are useful in photography, particularly as sensitizing dyes employed to extend the spectral sensitivity of gelatino silver halide emulsions in the manner known to'the art. More specifically, they are particularly useful as sensitizing dyes for use in composite emulsions having two emulsion layers with markedly different gradations which are selectively sensitized to different regions of the spectrum. In addition, the compounds are useful in color photography for the preparation of bleaching out layers in which the dyes are unstabilized to light and can be bleached to form colored pictures by one or more of the processes known to the art. The products of the invention are also useful in the preparation of colored filter or screening layers both for photography and other fields of optical science. Because of their resinous nature many of' the products contemplated in the invention are useful in the preparation of foils, films, and coatings wherein they may be mixed with various hydrophilic colloids or similar materials, or they may be used alone to produce the desired film or coating element.

In some instances self-supporting films of the novel dyes can be made. Those types having colloidal properties might be used to replace gelatin and similar substances for photographic elesalts.

with light sensitive salts. They could, furthermore, be used as filterlayers, color layers, antiabrasion layers, backing layers, etc.

The novel polymeric dyes can be used in conjunction with emulsion hardening agents, emulsion desensitizers, surface modifiers, fog-inhibiting agents, etc.

One of the most important advantages of the invention fromthe standpoint of photographic utility is that it permits the adsorption of sensi- 'tizing dye molecules on silver halide grains in multi-molecular layers of controllable depth and configuration. Of comparable advantage is the fact that the invention provides a series of cyanine-type sensitizing dyes which are non-wandering or substantially non-diifusible through the hydrophilic colloids such as gelatin which comprise the binding materials of silver halide emulsions. True, non-wandering, sensitizing dyes permit mixed halide'emulsions to be prepared having outstanding'properties for sharply recording individual spectral bands. A further advantage isthat the invention permits the preparation of photographic layers from self-bind- "ing dye materials which form cohesive resistant films suitable for light-sensitive silver halide layers, bleachable dye layers or filter layers. A

still further advantage is that the invention provides-dyes of the cyanine class substantive to materials which normally could not be dyed. An-

other advantage resides in the fact that the.

invention makes possible the preparation of highly colored films, foils, filaments-and plastics gen atom terminal to the conjugated chain of atoms of each by a hydrocarbon radical, theterminal nitrogen atoms being attached to a carbon atom of said hydrocarbon radical taken from the group consisting of aliphatic and cycloaliphatic carbon atoms.

- '4. Aphotographic silver halide emulsion containing a polymeric sensitizing dye having at least two molecules of a cyanine dye salt linked together through a heterocyclic nitrogen atom terminal to the conjugated chain of atoms of each by a hydrocarbon radical of the formula (CH2)n where 11. is an integer from 1 to 6 inclusive.

5. A photographic gelatino silver halide emulsion containing a polymeric sensitizing dye having at least two molecules of a cyanine dye salt linked together through a heterocyclic nitrogen atom terminal to the conjugated chain of atoms of each by a hydrocarbon-radical of the formula in which the dye molecule is an integral part of I the synthetic material.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by theappended claims.

This application is a continuation-in-part of copending application Serial No. 409,433, filed- September 3. 1941.

Iclaim:

1. A photographic silver halide emulsion containing a polymeric sensitizing dye having at least two molecules of a cyanine dye salt linked together through a heterocyclic nitrogen atom terminal to the conjugated chain of atoms of each by a hydrocarbon radical, theterminal nitrogen atoms being attached to a carbon atom of said hydrocarbon radical taken from the group con-.

sisting of aliphatic and cycloaliphatic carbon atoms.

2. A photographic silver halide emulsion containing a polymeric sensitizing dye having at least two molecules of a carbocyanine dye salt (-CH2)n where n is an integer from 1 to 6 inclusive. I v

6. In a photographic element comprising a support, a photographic layer containing silver halide grains having absorbed thereon a polymeric sensitizing dye having at least two molecules of a cyanine dye salt linked together through a heterocyclic nitrogen atom terminal to the con- Jugatedchain of atoms of each by a hydrocarbon radical, the terminal nitrogen atoms being attached to a carbon atom of said hydrocarbon radical taken from the group consisting of aliphatic and cycloaliphatic carbon atoms.

'7. In a photographic element comprising a support, a photographic layer containing silver halide grains having absorbed thereon a polymeric sensitizing dye having at least two molecules of a carbocyanine dye salt linked together through a heterocyclic nitrogen atom terminal to the conjugated chain of atoms of each by a hydrocarbon radical, the terminal nitrogen atoms being attached to a carbon atom of said hydrocarbon radical taken from the group consisting of aliphatic and cycloaliphatic carbon atoms.

CYRIL D. WILSON. 

